Remove all the wheels. CLEAN everything you see. Compressed air, solvent tank or leaf blower. Take an oily red shop rag and wipe it all down. Then another clean DRY rag and do the same. Reassemble and test. Easy right?
Don't oil or grease anything you see unless your manual states so. Mainly will attract dirt and grit wearing parts out faster.
Then remove the top engine cover and clean the block and fins like a NEW ENGINE.